Throttling process and device



Jan. 1, 1952 A. BRAMLEY} 2,531,168

THROTTLING PROCESS AND DEVICE Filed Jan. 12, 1948 5 Sheets-Sheet 1INVENTOR ATTO R N EYS Jan. 1, 1952 A. BRAMLEY 2,581,168

THROTTLING PROCESS AND DEVICE Filed Jan. 12,- 1948 I Y 5 Sheets-Sheet 2k l// Y 28:

/ z INVENTOR Jan. 1, 1952 A. BRAMLEY .THROTTLING PROCESS AND DEVICEFiled Jan. 12, 1948 5 Sheets-Sheet 5 INVENTOR ATTO R N EYS I an- 1952 A.BRAMLEY 2,581,168

THROTTLING PROCESS AND DEVICE Filed Jan. 12,- 1948 5 Sheets-Sheet 4lNVENTOR 95 w l Mos,

THROTTLING PROCESS AND DEVIE Filed Jan. 12,, 1948 5 Sheets-Sheet 5DIRECTION 01: (1A5 LEAvmq FLUTING DIRECTION OF Ra'rATlQN 0F F-UTINCI.

INVENTOR ATTORNEYS Patented Jan. 1, 1952 UNITED STATES PATENT OFFICE2,581,168 THROTTLING P OCE S AND DEVICE Arthur Bramley, Long Branch, N.J. Application January 12, 1948, Serial No. 1,728

11 Claims.

The present invention relates to processes of throttling and. of heattransfer and refrigeration thereby, and to apparatus suitable for this,Durpose.

' A purpose of the invention. is to permit the separation of compressedgas orvapor into hotter and colder fractions without the necessity ofmotion of the mechanism, or with motion of only a portion of themechanism.

A further purpose is to accomplish swirling and Darati0n into hotter andcolder fractions in a swirl chamber which is partially or whollystationary, building up a peripheral velocity in the swirl which exceedsthe velocity of sound in the particular gas or vapor and accomplishingexit endwise of the swirl chamber.

A further purpose is to compress a gas or vapor, to bring a gas or vaporto an inlet under conditions of streamline flow, to cool the gas orvapor preferably by substantially adiabatic expansion in a nozzle of theinlet, with resultant acquisition of high velocity, to introduce the gasor vapor through a mouth of the inlet into a swirl chamber with the axisof the swirl generally conforming to the axis of the swirl chamber andthe periphery of the swirl generally following the contour of theperiphery of the hamber, to build up a velocity in the swirl'suitabl'yat the periphery which exceeds the velocity of sound for the particularga or vapor, to p fe ably e ert a rea d preSSlire on the outside of theswirl compared to the pressure at the axis in excess of one-halfatmosphere due to centrifugal force, to cause the 'hgtiter molecules todo work against the pressure gradient, to Withdraw the hotter and coldertractrots throu h Xits endwise of he sw r chamber bearing relations asherein set forth, and to pass the hotter fraction through aconstrictien,

A further purpose is to provide an exit forthe colder fractionthrough anend wall of the swirl chamber which is not removed from the mouth bye isan e exce of hr t mes th mou h diameter, which is relativel lose to theaxis an extends over a relat ve y small r area and to conduct the hotterfraction through an exit in an end wall, preferably the opposite endwall, at least in part further from the axis and extending over arelatively larger area.

A further purpose is to provide a valve the exit of the hotter iractionto permit regulation of the" constriction so as to adjust the relativevolumes and temperatures or the two fractions and to adj s the'speed fhe r o whe 's r to is., mp. y d, the valve pre e' y' e is l mitednotcloser to the swirl chamber than ten times the diameter of the swirlchamber. Y I

A further purpose is to provide a generally cylindrical open interiorswirl chamber which has straight transverse end Walls in one form andcone-shaped end walls with the cones cooperating in another form, thelength of the chamber being inanycase small as compared 'to itsdiameter.

A further purpose is to separate condensable fluid before swirling.

A further purpose is to insulate the walls between the hot and coldexits.

A further purpose is to precool the compressed gas or vapor aftercompression, whether or not it is to becooled by adiabatic expansion inthe inlet means, and preferably to employ the colder fraction or aportion thereof, preferably also with the cooled hotter fractioncombined therewith, for precooling.

A further purpose is vto introduce the compressed gas or vapor into theswirl chamber as a jet or j'ets' tangential to the periphery and locatedin the circumferential wall. A further purpose is to maintain a diameterof the cold exhaust which is between one-half and one-third thediameterof the swirl chamber.

A further purpose is to employ a diameter of the swirl chamber which isbetween four and five times the diameter of the mouth of the singlenozzle, or the equivalent single nozzle of the multiple nozzles, orother inlet'means. I

A further purpose is to utilize an inlet gas pressure on the nozzle ofbetween 1.9 and 20 atmospheres, in many cases exceeding threeatmospheres.

A further purpose is to utilize an adiabatic nozzle having an abruptconverging portion, a throat and a diverging portion having a lengthabout five times the difference between the throat diameter and themouth diameter.

A further purpose is to employ jets in an end wall disposed at an angleto the wall and creating a swirling component for producing the swirland for rotating a rotor and also an axial component p erably upwa l oup o t r floa a rotor- A further purpose is to provide blades on thepreferably cone-shaped end of a rotor forming part of the swirl chamberand to rotate the rotor by jets entering the swirl chamber andpreferably supporting or floating the rotor upwardly on a verti al axis.

A further purpose is to reduce the temperature of the hot gases bycausing them to do Work on a rotating wall of the swirl chamber.

A further purpose is to space the rotor and stator cones by a distancetransverse to the rotor cone face between one and three times thediameter of the mouth of the individual inlet means (singe nozzle wherethere are multiple nozzles).

A further purpose is to provide exit for the hotter fraction around therotor endwise in an exit passage, the diiference between the inner andouter diameter of which at each side is between one and three times thediameter of the mouth of the individual inlet means (a single nozzle,where there are multiple nozzles).

A further purpose is to extend the blades on the rotor verticallyfarther than the vertical extent of the nozzles.

A further purpose is to employ a number of blades than nozzles.

A further purpose is to pick up gas or vapor from a heat transfermechanism, preferably with condensable fluid from a condensable fluidbath in heat transfer relation with the heat different transfer unit, tocompress the same, preferably to eliminate condensable fluid from thecompressed gas or vapor and preferably return the con- 'densable fluidto the bath of condensable fluid,

to cool the compressed gas or vapor, and to separate the condensed gasor vapor into fractions of different heat content as previouslyindicated, providing cooling of the heat transfer unit from the colderfraction and preferably also from the cooled hotter fraction, and alsoproviding cooling of the compressed gas or vapor at least in part fromthe colder fraction and preferably also from the cooled hotter fraction.

A further purpose is to introduce condensable fluid to the heat transferunit through a porous plug and permit return flow through the samemeans.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the variousembodiments in which my invention appears, choosing the forms shown fromthe standpoints of convenience in operation, satisfactory operation andclear demonstration of the principles involved.

Figure 1 is a diagrammatic view of a system to which the throttlingdevice of the invention ,may be applied, the form of Figure 1 beingequally applicable to either species.

Figure 1 is a diagrammatic longitudinal sec- ,tion of a detail of Figure1 showing the inlet chamber and porous plugs.

Figure 2 is a diagrammatic transverse section of the fully stationaryform of my throttling device, the section being taken on the line 2-2 ofFigure 3.

Figure 3 is a diagrammatic longitudinal section of Figure 2 on the line3-3.

Figure 4 is a diagrammatic central longitudinal section of the partiallyrotary form of my Figure 8 is a bottom plan view of the rotor in Figures4 and 5.

Figure 9 is a fragmentary elevation of the interior of the statorshowing the mouths of the nozzles, with the rotor positioned on the viewfor placement purposes.

into hotter and colder fractions,

The present application is a continuation in part of my copendingapplications Serial No. 632,825, filed December 5, 1945, for CentrifugalDehydrating and Cooling System; and Serial No. 706,739, filed October30, 1946, for Dehydrating, Liquefying or Cooling Gas and Air, which inturn are continuations in part of my applications Serial No. 417,960,flied November 5, 1941, for Centrifuge and Method, and Serial No.464,509, filed November 4, 1942, for Separation of Fluids bySimultaneous Centrifugation and Selective Diffusion, Patent No.2,422,882, granted June 24, 1947, all incorporated herein by reference.The present subject matter relates to the stationary or partiallystationary swirl chamber form, whereas my application Serial No.632,825, aforesaid, involves a fully rotary form.

The present invention relates to methods and apparatus for throttlinggas or vapor to separate the use or vapor into fractions of diiferentheat content. It will be understood wherever reference is made herein togas that vapor is also included, as well as mixtures of gas and vapor. s

It will be evident that the gas or vapor employed herein might be air,nitrogen, hydrogen, helium, argon, oxygen (using ordinary precautions),ammonia, carbon dioxide, freon, methyl chloride or other suitable mediumwhich would remain in gaseous phase under the operating cycle chosen. I

It is known that it is possible to changethe heat content of a gas bycooling while at the same time reducing the pressure of the gas in aturbo-cooler, as for example that of Kapitza, U. S. Patent No.2,280,585. Such devices involving very high speeds of turbo-rotors, withsmall clearances, present very serious mechanical problems ofconstruction and maintenance, which have interfered with the generalapplication of these machines. There are also num erous methods forchanging the heat content of a gas without any appreciable change inpressure, as for example the Norst Heat Engine. See A. M. Moody, 16 J.App. Phys. 551 (1945).

The present inventor has discovered that gas revolving in a high speedswirl can be separated and that providing certain conditions are met asset forth herein, the separation can be accomplished in a practical andeflicient manner. This result is obtained because the hotter and fastermoving molecules push away from the center of the swirl, while thecolder and slower moving molecules are trapped in the swirl andeventually find their way to the center. The hotter molecules are oftengenerating still further hotter molecules as they push away from theaxis of the swirl by doing work against the pressure gradient.

The present inventor has discovered that when the peripheral velocity ofthe swirl exceeds the velocity of sound in the particular gas or vapor,a very unusual effect occurs, by which the colder fraction becomesmarkedly colder and the hotter fraction becomes markedly hotter, greatlyincreasing the practicability of the device and process. It has alsobeen discovered that with increase in the temperature difference betweenthe hotter and colder fractions a smaller volume of the gas is cooled tothe temperature of the colder fraction. The present inventor hasdiscovered, however, that machines which are most eflicient for reducingthe heat content of the separated gases operate at small temperaturedifferentials.

For best results the gas or vapor which is to be separated into hotterand colder fractions should contain no condensable fluid which willproduce condensable liquid. For example if the gas be air, thecondensation of water vapor present in the air will reduce theeiliciency of the machine to a marked extent.

For most efiicient operation the portion of the swirl chamber in contactwith the colder fraction and the portion in contact with the hotterfraction should be heat insulated from one another so that heat flowthrough the material of the swirl chamber wall will not tend to equalizethe temperature differential.

It is important that the swirl chamber be circular (cylindrical) andthat it have an open interior so that the swirl can follow the generalcontour of the periphery substantially around the axis of the swirlchamber without formation of eddies which will dissipate kinetic energyas heat. The inlet should be so designed that a peripheral velocity inexcess of the velocity of. sound can be built up in the swirl as laterexplained. While other suitable inlets may be employed, the preferredinlet is through a substantially adiabatic nozzle, having first a regionof sharp convergence,

then a minimum or throat and finally a region of. more gradualdivergence, preferably having a length about five times the differencebetween the diameter of the mouth and the diameter of the throat throughwhich the nozzle discharges (see Everett, Thermodynamics, chapter VIIIand Stodola, Steam and Gas Turbines, Volume I, section 19, and chapterX, section 167). The. critical pressure ratio above which the nozzlemust function is 1.90 for air.

If the gas or vapor is introduced into the swirl chamber at high speedbut at moderate temperature, such as room temperature, the temperatureof the colder fraction will be markedly higher than if the gas or vaporis cooled before introduction. The cycle may be carried out in variousways. The initial cooling of the gas or vapor after compression andbefore entry into the swirl chamber at high speed may be accomplished bya precooler using as a coolant a part of the colder fraction from theswirl chamber, or may be accomplished by an adiabatic nozzle in theinlet to the swirl chamber or by a turbocooler or any combination ofthese. By this procedure a continuous lowering of the initialtemperature of the compressed gas takes place, which is very desirablewhere the colder fraction is to have the lowest possible temperature.

In the preferred embodiment, condensable fluid such as water vapor willbe removed from the gas or vapor before it enters the throttling device.Conventional devices such as water eliminators may be used for thispurpose.

The swirl space is circular (cylindrical) and has an open interior so asto permit swirling unimpeded. The end walls of the chamber in which thegas or vapor swirls may be straight and transverse or may be frustums ofa cone. Where the straight transverse ends are used the inlet willpreferably be tangential through the periphery, but where the conicalends are employed the inlets are preferably placed not at the peripherybut in an end wall at a distance from the periphery, and are oriented soas to the swirl.

produce a radial component outwardly and a component in a directionparallel to the axis and away from the end wall through which the inletis accomplished.

The conical form will preferably have its axis vertical and will beprovided with a rotor in one (desirably the upper) end wall which willrotate due to the swirl and preferably be supported on the jet or jets.The end wall rotor is suitably provided with blades or flutings on theconical surfaces which are oriented with respect to the direction of thejet or jets so that the gas or vapor does work on the rotor lowering itsheat content. e

In the various forms a constriction is provided in the exit forthe-hotter fraction, preferably as a valve which can be adjusted'todetermine the temperature difference and volume relation between thehotter and colder fractions. Where the rotor is used the valve will alsoregulate the speed of rotation.

The swirl chamber will have a length which is short compared to thediameter, the critical fea. ture being that the inlet mouth is quiteclose to the end wall through which the exit for the colder fractionleaves the chamber. The mouth distance from the end wall through whichthe colder fraction leaves the chamber will not exceed three times themouth diameter, and in many cases the mouth will be directly in linewith the end wall at one side, or actually in that end wall. The mouthdiameter here referred to is the diameter of the individual mouth (oneof several, where multiple nozzles are used).

Only in the line of the nozzle mouth is the velocity a maximum. As onemoves away from that region in the direction parallel to the axis nearthe periphery, the velocity of the stream falls. In such region of lowerpressure along the periphery, the gas becomes hotter due to diffusion ofhotter molecule out of the high speed gas stream. In the direction ofthe hot exhaust, the hotter molecules are drained off, but in the direction of the cold exhaust the hotter molecules would diffuse into thecold stream and raise its temperature, defeating the purpose of thedevice,

if space were left for them to accumulate. The limitation of thedistance between the mouth and the end which contains the cold exhaustserves to limitthe entry of hotter molecules into the colder fraction.

The swirl will build up a pressure in the outside due to centrifugalforce which will exceed'the pressure at the axis of the swirl by atleast onehalf atmosphere and usually by three-quarters of anatmosphere.- This is due to the fact that the velocity of the swirlexceeds the velocity of sound, and to the fact that at room temperaturethe molecular weight of the gas under" consideration is less than orequal to that of air. The pressure p at the periphery of the swirl isrelated to the pressure p0 at the axis as follows:

I M 2rz p-Po P W where M is the molecular weight of the gas, R is thegas constant, T is the temperature, I is the: radius of the swirlchamber,

is the frequency in revolutions per second, and

w'y is the peripheral velocity. Hotter molecules must do work againstthe pressure gradientin .7 v f: The exits .from the swirl chamber willextend endwise and preferably parallel to the axis, but will havedifferent areas and extend to different distances from the diameter. Theexit for the colder fraction will also be in a wall which is close tothe mouth as above indicated. Of the two exits, the exit for the colderfraction will be closer to the axis and the exit for the hotter fractionwill extend at least in part farther from the axis. Of the two exits,the exit for the colder fraction will have the smaller cross sectionalarea as it leaves the swirl chamber. The two exits will be preferably,but not necessarily, coaxial with the chamber.

The preferred diameter of the exit for the colder fraction will bebetween one-half and onethird the diameter of the swirl chamber, as ithas been found that turbulence is minimized in this way. The preferreddiameter of the swirl chamber is between four and flve times thediameter of the inlet mouth, in order to obtain most efiicient results.In this case the diameter of the mouth where multiple nozzles are usedis the diameter of the mouth of the single nozzle which will pass thesame amount of gas at the same speed as the multiple nozzles (called thesingle equivalent nozzle). In the case of a single nozzle, the singlenozzle and the single equivalent nozzle are the same.

Considering first the throttling device of Figures 2 and 3, the swirlchamber as is cylindrical, having an axis 2!, a circumferentialperipheral wall 22, a straight transverse cold end wall 23, and astraight transverse hot end wall 24. The interior of the swirl chamberis entirely open and unimpeded 'by vanes, partitions, walls or structureof any other character.

Inlet to the swirl chamber is accomplished through the inlet means 25,here shown as a nozzle. It will be understood that any suitable numberof nozzles may be used, the drawing being limited to the illustration oftwo nozzles, rather than to one, three, four or some other number inorder to simplify the illustration, and multiple nozzles being shown inFigures 4 to 9, intended to indicate that they may be used in any of theforms.

The preferred embodiment has the nozzle tangentially directed to theswirl chamber as shown so that it will impinge upon the periphery of theswirl 26 which rotates in the swirl chamber on the axis 2!. Each nozzlehas an approach portion 21 through which streamline iiow is preferablyobtained, a converging portion 28, a throat 29, adiverging portion 30and a mouth 3|. The nozzle is preferably an adiabatic expansion nozzle,in which case the diverging portion will preferably have a length ofapproximately five times the difference between the mouth and the throatdiameters.

The adjoining edge of the mouth is distant from the cold end wall 23 notin excess of three times the mouth diameter (the actual, not theequivalent mouth diameter). In the present case the spacing is only afraction of the mouth diameter.

The diameter of the swirl chamber is preferably between four and fivetimes the mouth diameter. In this case, where several nozzles are used,the mouth diameter is that for the equivalent single nozzle.

Located relatively close to the axis, having a relatively smallerdiameter, and extending through the cold wall endwise, is an exit 34 forthe colder fraction. Arranged in one of the end particular walls andpreferably in the opposite end wall, and extending endwise andpreferably axially, is an exit 35 for the hotter fraction, which extendsat least in part to a greater diameter or distance from the axis thanthe exit for the colder fraction and which has a larger area. When it isstated that the exit for the hotter fraction extends at least in part toa greater diameter, it is intended to indicate that the portion of theexit 35 near the axis may be optionally open or closed, but some portionof the exit for the hotter fraction will extend farther from the axisthan the exit for the colder fraction, and the over-all area of the exitfor the hotter fraction as it leaves the swirl chamber will be greater.

The coaxial arrangement with respect to the exits and with respect tothe chamber is preferred.

The relations given for the dimensions of the mouth, the swirl chamberand the exits assure efficiency great enough to make the devicepractical and the preferred ranges as above specified insure thatmaximum efficiency will result.

The material and thickness for the swirl chamber walls should be chosenso that heat conductivity will be reduced to a minimum. Thus the wallsare to advantage made of plastic, such as phenol formaldehyde or acrylicplastic, glass or ceramic, where the pressures will permit, or areconveniently made of metals such as stainless steel, Nichrome, orinconel having lower heat con ductivity, or of metals having enameled,ceramic, plastic or rubber coatings to reduce heatjconductivity. I

The annular peripheral wall 22 of the swirl chamber may desirably have athickness sufficient so that all or part of the inlet can be constructedin the wall, as for example by makin the entire nozzle or nozzles asports in the wall, or by forming a portion of the nozzles as such ports.

In the form shown, the nozzles are constructed as inserts in theperipheral wall 22. The length of the channel as compared with itsdiameter and the shape of the channel depend upon the design used. Inthe preferred form for adiabatic nozzles the length of the portion 30 isabout five times the difference between the mouth and the throatdiameters. In order to permit the adiabatic nozzle to operate above thecritical pressure ratio between the initial pressure and the throatpressure of 1.90, the channel 30 from the throat to the mouth shouldpreferably diverge at an angle of about ten degrees, with a very shortrapidly converging portion 28 from the nozzle inlet to the throat, whichshould preferably have a length of about one-twentieth of the length ofthe diverging portion.

The passage 21 which supplies the gas or vapor to the nozzle or nozzlesshould preferably have a diameter large enough compared to the diameterof the mouth so that gas or vapor flows in the passage 21 at arelatively slow rate, less than the velocity of sound in the particulargas or vapor, and preferably less than about a thousand feet per minutein air, so that it does not tend to heat up by friction effects. Theapproach passage 2'! will therefore have streamline flow. The limitingvalue of the velocity v, for which streamline flow is possible, is givenby the expression:

where ,0 is the density, d the diameter of the approach passage 21 and ais the absolute viscosity. See Marks Engineering Handbook (4th edition,

slightly higher than the colder exhaust.

assume 9 19411, 265. Frictional heat should be avoided at this stage asit counteracts the cooling effect and represents waste energy.

It is very important that the exit speed at the mouth and the peripheralvelocity of the swirl exceed the velocity of sound in the particular gasor vapor. Thus in air the exit speed and peripheral velocity will exceedten hundred and eighty feet per second, the acoustical velocity. Toobtain this acoustical velocity his best to employ the adiabatic typenozzle already described, so that the ratio of the initial pressure tothe throat pressure exceeds 1.90 (Everett, Thermodynamics, chapter VII).'I'husthe gas or vapor is preferably substantially adiabaticallyexpanded in the nozzle with resultant cooling and acquisition of highvelocity.

The feature of reducing the temperature of the gas and increasing thekinetic energy can be accomplished by devices other than the typicaladiabatic nozzle referred to, such as the De Laval nozzle- The swirl inthe swirl chamber 20 will exert centrifugal force when the periphery ismoving above the acoustical velocity, so that the outer swirl issubjected to an increased pressure as compared to the axis of the swirlwhich will be in excess of one-half atmosphere and preferably of theorder of three quarters of an atmosphere (these are practical values forseparation into fractions of different heat contents as explainedherein).

During the operation of the swirl, the faster molecules are compelled todo work against this pressure gradient, thus lowering their heatcontent.

The exit 35 of the hotter fraction has a constriction 36, preferably inthe'form of a valve .to permit adjustment. For most efiicient operationthe constriction should be located at a distance from the swirl chambernot less than ten times the diameter of the swirl chamber in order toreduce turbulence of the hotter fraction, and

obtain the best results in adjusting the volumes of the fractions andthe temperatures relative to one another.

.The gas or vapor through the passage 21 will normally be at asubstantial pressure, ordinarily from 1.9 to 20 atmospheres, and usuallygreater than three atmospheres. 1 Higher pressures may be used.- Theexit of the hotter fraction at 35 will normally be at a low pressure,

usually not much above atmospheric pressurabut The minimum inletpressure for effective operation of the device will vary depending uponhow many nozzles are used and the character of nozzle, but it should besufficient to maintain a peripheral velocity of swirl in excess of theacoustic velocity and to maintain a difference in pressure between thecircumference and axis of the swirl in excess of one-half atmosphere andpreferably of the order of three quarters atmosphere or greater.

The colder fraction leaves itsexit 34 at a pressure which will beatmospheric in many applications. Of course, it will be evident that ifthe device is working on a closed cycle, the colder and hotter fractionsmay be exhausted at higher or lower pressures provided there be asufficient pressure differential between the pressure of the colder andhotter fractions and the pressure in the approach passage 2?.

In case-the inlet gas or vapor contains an appreciable amount ofcondensable vapor such as water vapor, which is not eliminated beforethe 10 gas or vapor reaches the inlet mouth, the temperature drop foradiabatic flow in the diverging portion of the adiabatic nozzle will bedecreased considerably since the heat of condensation is in generallarge as compared to the specific heat in various gases or vapors.

In many applications the hotter exhaust will be at a comparatively hightemperature, and heat insulation is therefore rather important in suchcases. Where the pressures are such that the walls of the swirl chamberand. the adjoining hotter and colder exhausts must be made of metal, itis preferable to avoid metals of high conductivity such as copper andaluminum and to employ metals of lower heat conductivity such asstainless steel, Nichrome or inconel. For many installations heatconductivity can be further reduced without departing from metal as aconstruction material by employing ceramic, enamel or other coatings oflower heat conductivity on the walls of the interior of the swirlchamber and the hotter and, colder exhausts. For installations where thepressure is low enough, or for portions of the walls which are subjectedto lower pressures, it is satisfactory and from the standpoint of heatconductivity it is very advantageous to construct the device of plasticsuch as phenol formaldehyde, urea formaldehyde, or acrylic resin, or ofglass or ceramic.

For many types of installations it has been found satisfactory to makethe diameter of the swirl chamber of the order of three-quarters of aninch. The diameter of the swirl chamber ordinarily will not greatlyexceed one and onehalf inches. Successfulresults are obtained with swirlchamber diameters as small as one-half and one-third inches. Thenozzlemouth diameter has in some cases been one-sixteenth of an inch andin individual installations has varied from one-tenth toone-thirty-second of an inch. The peripheral wall of the swirl chamberhas in individual cases been one-eighth to one-quarter of an inch thick.Thenumber of nozzles equally spaced tangentially around the swirlchamber in the preferred embodiments may vary from one to six. The flowin the exits has preferably been in the order of about one hundred feetper minute, as contrasted with a peripheral velocity in the swirl inexcess of the acoustical velocity.

In anindividual test on a device of the character shown the followingdata were taken:

Room temperature, 17 C.

Pressure of inlet air, p. s. i.

Temperature of inlet air at ambient.

Volume of free air flow, ten cubic feet per minute.

Temperature of cold fraction, 4 C. I

Temperature of hot fraction, 38 C.

Volume of free air cold fraction, 5 cubic feet per minute.

Volume of free air hot fraction, 5 cubic feet per minute.

As shown in Figures 4 to 9; inclusive, a part of the wall of the swirlchamber may move. Thus the temperature of the hotter fraction can bereduced if the end wall of the chamber through which the hot gas orvapor is exhausted is designed so that the hot stream of gas or vaporcan do work upon the end wall. When such end wall is made to rotatewhile engaged by the gas or vapor jets, the whole mass of gas or vaporassumes a lower average temperature.

As shown in Figures 10, if the direction of rotation of the fluting is31, the blade or fluting on which the work is done by the gas is 38, andthe direction of the gas leaving the fiuting is 39. Figure 11 representsa velocity vector diagram showing the work done by the gas or vapor onthe fluting. V1 represents the velocity of the gas jet striking thefluting at an angle a with respect to the direction of rotation 31. Vbis the velocity of the fiuting. Vlf is the velocity of the jet of gas orvapor striking the fluting expressed with reference to the fluting. Theangle ,3 represents the true angle at which the stream of gas or vaporenters the fluting. If the gas or vapor encounters no friction, itleaves the fluting at the same speed vlf and at the same angle 5relative to the fiuting. The absolute velocity of the gas leaving thefluting is obtained by laying out again Vb and closing the triangle. Theabsolute velocity of the gas leaving the fluting is V2 and it makes anangle 6 with respect to the direction of rotation of the fiuting. Theforce F produced by changing the direction of motion of the gas jetinvolving W pounds of gas per second, where g is the acceleration ofgravity, is.

W(V1 cos a+V2 cos 6) 9 The work done through the distance Vb which thefluting travels per second is therefore:

This is work taken from the kinetic energy of the gas stream.

The design may be varied in respect to the shape of the end walls, theorientation of the jets with respect to the end walls and the design ofthe'flutings or blades which act as the blades in a gas turbine.

The device of Figures 4 to 9 functions in general in the same manner asthedevice of Figures 2 and 3. The rotor 40 rotates on a gas cushion .43in the swirl chamber 20' provided between the rotor 40 and the statorcone 44. The periphery of the generally circular swirl chamber iscircular at 22, but the cold end wall 23' and the hot end wall 24' areconical and preferably conform approximately to the same Gas or vaporcompressed suitably to a pressure preferably between 1.9 and 20atmospheres or higher, and usually above three atmospheres andpreferably cooled to room temperature is held in an annular reservoir 45in the stator. From the reservoir the compressed gas flows through inletmeans 25, preferably one of a se- "ries of adiabatic nozzles, as alreadydescribed.

to a velocity at the mouth which exceeds that of sound.

The distance between the end wall 23' of the stator and the end wall ofthe rotor measured transversely to the cone face on the rotor should notexceed three times the diameter of themdividual nozzle mouth (not theequivalent nozzle) and should not be less than one times the diameter ofthe mouth, so that thejets of gas from the nozzle do not becomeexcessively diffuse before impinging on the radial fiutings of therotor. Since the rotor is floating this can be adjusted by the weight ofthe rotor in relation to the pressure.

In some cases it may be desirable to make the cone angle 46 of the rotorslightly different from the cone angle of the stator to compensate forinequalities in air flow, but in the form shown the two cone angles havebeen made the same. i

As best seen in Figures 4, 6 and. 8 the end wall 24 of the rotor isfluted with blades or channels 41 distributed radially around the apexof the rotor. The flutings or blades terminate at a distance E from theapex which is small as compared to the diameter D. The fiutings extendto a height C above the apex which is greater than the height B of thenozzle exits from the same. In the preferred embodiment, the flutingsextend over the bulk of the radial extent of the end 24, and extendgenerally in a radial direction along such end wall.

With the particular axial length of the flutings and the speed ofrotation, the gas or vapor striking the flutings should do an amount ofwork which is appreciable as compared with the kinetic energy of the gasor vapor. If thenumber of nozzles is n, the number of flutings should benmil, where m is an interger, such as l, 2, 3, etc. I

The hot fraction of the gas escapes through the exhaust exit 35',provided in the clearance between the outside circumference 48 of therotor and the tubular wall 49 of the exit. This clearance should conformto the dimensions specified for the hot gas exit in the previousdiscussion, but it has been found that a clearance of a few tenths of aninch (ordinarily not over one-half inch) is ample in most installations.This clearance all around the rotor can to advantage in manyapplications vary between one and three times the diameter of the mouthof the individual nozzle (not the equivalent nozzle). A constriction 36'in the form of a valve is placed a distance above the rotor whichexceeds ten times the diameter of the swirl chamber in order to reduceturbulence and friction. Adjustment of the valve permits adjustment ofthe relative volumes and temperature of the hotter and colder fractionsand of the speed of the rotor.

The cold fraction is exhausted through the cold exit 34' which joins thestator cone adja-- cent to the apex thereof and extends in an axialdirection.

The orientation of the inlet means 25' is such that the gas streamleaving the jets does a maximum of work on the rotor. For the flutesshown in Figures 4 to 9, the nozzles 25 should desirably make an angleof about 45 with the vertical as shown in Figure 9, assuming that theangle at the apex of the rotor is as shown. The jets are arranged withrespect to the fiutings of the rotor so that the resultant effect is adownward acceleration on the rotor which opposes the upward forceresulting from the deceleration of the gas stream on the lower surfaceof the rotor. The rotor is pushed down toward the stator cone becausethe atmospheric pressure (or whatever 13 the exhaust pressure may be) onits top is greater than the average pressure on the lower surface. Atthe axis of the rotor the pressure is close to atmospheric (or to theparticular exhaust pressure) whereas at the region of the maximum of theswirl where the gas is moving with high velocity after just leaving thenozzles, the pressure is low. According to Bernoullis theorem, thepressure P and the velocity V are connected by the following equations:

where y is the specific weight of the gas and g is the acceleration dueto gravity. Where the velocity V is negligible, as for example at theaxis, because the nozzles are directed outward, the pressure Papproaches the atmospheric pressure (or the particular exhaustpressure), whereas, where V is of the order of the acoustical velocity,the pressure falls a fraction of an atmosphere.

Good results may be obtained with variation of the orientation andspacings of the jets and fiutings from those described above.

In the partial rotor form, because of the high speeds involved, therotor should preferably be of metal (such as stainless steel, Nichromeor inconel) but the other parts of the equipment may be of the materialspreviously mentioned.

In the particular device in a specific embodiment, the rotor is aboutone inch in diameter and has a clearance from the stator at thecircumference of about one-eighth inch all around. In operation thefollowing data were obtained:

Number of nozzles, 7.

Numberof blades, 8.

Pressure of the air in the reservoir, 50 p. s. i.

Room temperature, 81 F.

Temperature of the compressed air at ambient.

Temperature of the cold fraction, 64 F.

Temperature of the hot fraction, 86 F.

Speed of the rotor between 500 and 1,000 revolutions per second.

In this form, the rotor floated on gas as it turned.

In both of the forms of the invention as described, the inlet gas orvapor is compressed to a reasonably high pressure, preferably in excessof about three atmospheres, and is carried to the point of inlet to thethrottling device preferably under streamlined flow. Inlet isaccomplished through a mouth which is preferably the mouth of a nozzlesuitably of adiabatic type. In the nozzle the gas is cooled and.increased in velocity so that at the mouth of the nozzle and in theperiphery of the resulting swirl, the velocity exceeds the velocity ofsound in the particular gas or Vapor. If a nozzle is not used, andpreferably where a nozzle is used, the gas or vapor will be cooledbefore it passes through the nozzle.

The swirl chamber is open in interior and of circular or cylindricalshape so that the swirl forms about the axis of the chamber. Thepressure in the periphery of the swirl of the stationary form isincreased by the centrifugal force in excess of about one-halfatmosphere and the faster molecules are caused to do work against thepressure differential. The mouth of the nozzle is distant from the endwalls through which the cold exhaust takes place not in excess of threetimes the diameter of the mouth of the individual nozzle. The coldexhaust takes place closer to the axis and over a relatively smaller 14area than the hot exhaust which takes place: at least in part furtherfrom the axis and over a relatively greater area. Flow" in the hotexhaust is constricted. 1

In the preferredembodiment the diameter of the cold exhaust. ispreferably between one-third and one-half the diameter of the swirlchamber to minimize turbulence. The diameter of the swirl chamber ispreferably between 4 and 5 times the diameter of the equivalent nozzlemouth (the nozzle which passes the same amount of gas or vapor at thesame speed as thetotal of the multiple nozzles) It should be emphasizedthat the throttling device of the invention does not cool the gas afterit enters the swirl chamber through the nozzles. The gas in thepreferred embodiment is cooled as it passes through the adiabaticnozzles, but it will be understood, of course, that advantage from theinvention can be obtained by cooling the gas in any other suitablemeans, for example by one of the turbo-expanders known in the art, andthen passing the .gas; at velocity in excess of that of sound directlyto the swirl chamber for separation into hot and cold components. Theimportant feature to consider, however, is that the function of theswirl chamber is to sort out gas or vapor molecules into two separatefractions, one with high and theother with low kinetic energies. Thecolder molecules with low kinetic energies remain colder while thosewith high kinetic energies become heated through degradation of kineticenergy into thermal energy and are exhausted as the hot fraction of thegas. In the embodiments illustrated the inlet channels are soconstructed that together with the entrance opening they function asadiabatic nozzles. H

Figure l is a flow sheet of a throttling unit which may be of either ofthe types shown, applied to cooling a refrigeration load, in this case awater bath. The water bath 54 is contained within a suitably closed tank55 which includes the Water bath and air or other gas or vapor. Inletfor air and water vapor to the system is provided by a pipe 55' from .aninlet chamber 56 to a compressor 51 driven in any suitable manner by apower unit 58 at a suitable speed to run the compressor efiiciently. Inthe wall of the inlet chamber is provided a series of ceramic plugs 59of any well known character (as for example the Selas type), porous towater but to a limited extent impermeable to air. The porous plugs 59are immersedbeneath the water of the water bath and permit how of watertherethrough back and forth between the water bath and the inlet, whileretaining the bulk of the air. in the inlet. Each plug is connected onthe inside to the inlet.

From the compressor the air and accompanying water are conducted througha pipe 60 to a water eliminator 63 of any well known type which may ifdesired be provided with a cooling coil 64 so that it can function as acooler or preliminary intercooler if necessary. Water taken off by thewater eliminator fromthe compressed air is disposed of in any suitableway as by manual removal, but preferably by I drainage through a returnpipe 65, to the water bath. so that it can return and replenish thewater in the water bath. It will be understood that reasonably goodefficiency in water elimination is desirable to obtain high efliciencyin the throttling device. From the water eliminator the compressed airis carried through a cooler 66 whose operation will be described, andfrom the cooler the cooled compressed air passes through a throttlingdevice 61, in accordance with the invention, and which may be of any ofthe types shown. From the throttling device 6! the colder fraction iscarried through an exit 88 while the hotter fraction, after passingthrough the constriction, leaves by the exit 69. In order to permitadvantage from the fact that the hotter fraction has been deprived ofpart of the water vapor content, it is desirable to cool the hotterfraction in an after cooler I8 having a cooling coil 13 to approximatethe ambient temperature. The hotter and colder fractions are thencombined at 14 and the combined fractions are first carried through thejacket portion 15 of the cooler 66, using part of the refrigeration tocool the inlet compressed air to the throttling device. From the cooler66 the remainder of the combined hotter and colder fractions are carriedthrough pipe 16 back to the inlet, where the air is again available togo throu h the next cycle.

Excess air may be drawn into the system by leaks at low pressure pointswhich would result eventually in building up an excessive pressure. Asuitable blow-ofi device 11 is provided on the high pressure side toeliminate air which might increase the inlet pressure above severalinches of mercury. It is found to be cheaper and simpler, rather thanusing a pressure blow-off valve of any of the well known types, toemploy a well-known plug at 11 which is porous to air and impermeable towater (for example of the Selas type) causing a constant slight leakageoutwardly which will make up for inlet leakage at other points.

In operation it will be understood that air accompanied by water vaporpasses through the compressor and is compressed, and the heat ofcondensation of the water is absorbed by the cooling medium in the watereliminator 63 or the cooler 66 or both, returning the water to the waterbath as liquid water. It is not necessary to go to the expense of makingan air tight closed cycle, and the air leaking into the system isutilized as effectively as possible. The air pressure in the water bathis preferably held at a level less than two inches of mercury, theexcess air being ejected from the system, as for example through theblow-off means 11.

In order to evaporate water in the water bath heat of evaporation mustbe supplied. In Figure 1 this heat is supplied from the water of bath54. In the water eliminator 63 part of this water is condensed andreturned to the water bath by the pipe 65, which returns only water, andnot any appreciable amount of compressed air. The heat given off oncondensing water vapor is taken away by cooling coil 64 so that the netresult is that the water bath has to supply heat and thus cool itself inthe evaporation process. The water bath is also cooled by the cooled airreturning by pipe 16. The return of condensed water back to the waterbath prevents depletion of the water in the water bath.

In view of my invention and disclosure variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the process and structure shown, and I,therefore, claim all such insofar as they fall within the reasonablespirit and scope of my claims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. In a refrigerating device, a compressor, a heat exchanger connectedto the high pressure side of the compressor, walls forming an openinterior generally circular swirl chamber which is at least in partstationary, inlet means including a nozzle having an abruptly convergingportion, a throat and a divergin portion having a length about fivetimes the difference between the throat diameter and the mouth diameterfor introducing gas or vapor from the compressor into the swirl chamberin a swirl whose axis conforms to the axis of the chamber, whose peripheral velocity exceeds the velocity of sound for the particular gasor vapor and whose pressure at the outside exceeds the pressure at theaxis by at least one-half atmosphere, the mouth being at least as closeas three times the mouth diameter to one end of the chamber, wallsforming exits extending endwise of the chamber for hotter and colderfractions, the exit for the colder fraction being through said end walland relatively smaller and closer to the axis and the exit for thehotter fraction being relatively farther from the axis, a connection forcarrying at least a part of the colder fraction into heat trans ferrelation with the heat exchanger and a constriction in the exit for thehotter fraction beyond the chamber.

2. A device according to claim 1, in which the walls forming the openinterior swirl'chamber are entirely stationary.

3. A device according to claim 1. in which one of the walls forming theopen interior swirl chamber is stationary and another of the wallscomprises a rotor rotated by the gas or vapor.

4. A device according to claim 1, in which the open interior swirlchamber is of conical form, with outlet for the cold fraction at thesmall end and for the hot fraction at the large end.

5. A device according to claim 1, in which the open interior swirlchamber is conical, and the upper wall thereof comprises a rotor whichis turned by the gas or vapor and floats on the gas or vapor swirl.

6. A device according to claim 1, in which the exit for the colderfraction and the exit for the hotter fraction are in opposite ends ofthe swivel chamber.

7. A device according to claim 1, in combination with means forrecycling a portion of said hotter fraction back to the inlet of thecompressor.

8. A device according to claim 1, in combination with a supplementarycooling unit and means for recycling said hotter fraction through thesupplementary cooling unit and thence back to the inlet of thecompressor.

9. A device according to claim 1, in combination with means forconveying the colder fraction back to the inlet of the compressor afterit passes in heat transfer relation with the heat exchanger.

10. A device according to claim 1, in combination with means forremoving condensed vapor from the fluid stream after it leaves theoutlet of the compressor and before it enters the swirl chamber.

11. In a refrigerating device, a compressor, a heat exchanger connectedto the high pressure side of the compressor, walls forming an openinterior generally circular swirl chamber which is at least in partstationary, inlet means including a nozzle having an abruptly convergingportion, a throat and a diverging portion having a to the axis of thechamber, the mouth being at 5 least as close as three times the mouthdiameter to one end of the chamber, walls forming exits extendingenclwise of the chamber for hotter and colder fractions, the exit forthe colder fraction being through said end wall and relatively small- 10er and closer to the axis and the exit for the hotter fraction beingrelatively further from the axis, a connection for carrying at least apart of the colder fraction into heat transfer relation with the heatexchanger and a constriction in the 15 exit for the hotter fractionbeyond the chamber.

ARTHUR BRAMLEY.

18 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 808,898 Oates Jan. 2, 19061,952,281 Ranque Mar. 27, 1934 2,522,787 Hughes Sept. 19, 1950 OTHERREFERENCES Industrial and Engineering Chemistry, May 10, 1946, Volume38, number 5, page 5.

Industrial and Engineering Chemistry, December 7, 1946, Volume 38,number 12, pp. 5, 8, 10, 12 and 14.

Journal of the A. S. R. E., July 1948, pp. 58 and 59.

